Paint & Coatings Industry - November 2008 - (Page 68)

Self-Crosslinkable Thermosetting Acrylics for Use in Water-Dilutable Coatings dynamic scans (from 0-600 °C at the rate of 20 °C/ min) of 13.4470 mg sample held under the dry flow of nitrogen at the rate of 30 ml/min. The refractive index of aqueous resin solutions was determined by an Abbe refractometer, at 25 °C. Viscosity of the aqueous resin solutions was determined by Brookfield cone and plate 2000 + viscometer, at 25 °C (w.r.t. spindle - 3). Solid content of aqueous solutions was checked as per ASTM D 1259. The results of characterization, along with the TSA resin designations, are presented in Table 2. thickness (DFT) of the coated film was maintained at around 30 µm (with the help of a bar applicator). DFT of the coated films was measured by a Positector 600 (Sheen, U.K.). The films were allowed to bake at the required temperature in an air-circulatory oven for effecting film cure. Then various optical, mechanical and chemical resistance properties of the cured films were evaluated as per standard procedures. Results/Discussion Chemical Structure IR-Spectra FTIR spectra of each TSA resin, obtained before neutralization, were almost the same. Figure 1 shows the IR spectrum of resin TSA4, which confirms the molecular structure of TSA resins in all aspects. The sharp band in the range of 2935 cm-1 may be due to C–H stretching vibration of methyl and methylene groups. Absorption at 1460 cm-1 is assigned to asymmetric –CH3 or –CH2 bending vibrations. A sharp band at 1717 cm-1 is attributed to C=O stretching frequency. A sharp broad band in the range of 3342 cm-1 is due to O–H stretching. A split peak at 1069 cm-1 might be due to C–O stretching of alcoholic and ester groups. The absence of a peak at 3000-3040 cm-1 and at 1600-1700 cm-1 indicates that no vinyl hydrogen is present in the final molecular structure of the polymer. 1H NMR-Spectra Coating Preparation The prepared water-thinned TSAs were used for the application of clear films on glass plates (5 cm × 10 cm) and tinned mild steel panels (5 cm × 15 cm). Dry film FIGURE 1 | IR-spectrum of prepared TSA4 resin. 55.3 50 45 40 35 %T 30 25 20 15 10 5 3342.82 2935.05 1717.38 1460.48 1069.52 653.79 1.4 4400.0 4000 3000 2000 cm-1 1500 1000 400.0 FIGURE 2 | 1HNMR spectrum of TSA4. 0.6 0.7 CH 3 C H COO Proton NMR spectra were all as expected, with resonance at 3.5 ppm [t, 4H, O-(CH2-CH2)-OH], the singlet peak at 4.8 ppm (s,H, OH), 1.4 ppm (Figure 2) and 0.6 - 0.8 ppm (Figure 2). The 1H NMR spectrum (Figure 2) of sample TSA4 was a close match to its theoretically elucidated structure. Thermal Behavior Differential Scanning Calorimetry (DSC) The curing characteristics were determined by DSC. A thermoset acrylic resin DSC thermogran is shown in Figure 3. The figure clearly indicates a sharp peak temperature range from 146 to 150 °C, which could be the curing temperature of the prepared TSA resin. Total heat required for this was 315 J/g. 2.71 C H2 0.5 -O-C H 2-C H 2-OH 0.4 C H2 CH C H2 0.3 C OONH 4 Thermogravimetric Analysis The thermal decomposition behaviour of organic polymers is commonly determined by TGA. The TG curve (Figure 4) reveals the weight loss of substances in relation to the temperature of thermal degradation. Figure 4 shows excellent thermal stability of the synthesized resin TSA4. TGA of the copolymer shows major weight loss at two stages. The first 0.2 -40.12m 0.62 0 10.0 9.0 8.0 7.0 6.0 5.0 4.0 0.22 0.1 3.0 0.76 2.0 1.19 O H 1.0 X : parts per Million : 1H 66 NOV EMBER 2008 | W W W . P C I M A G . C O M http://WWW.PCIMAG.COM

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Paint and Coatings Industry - November 2008 Contents Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News HiTone Resins for Enhanced Pigment Affinity of Powder Coatings New Water-Based Interior Coatings Combine Innovation and Quality With Respect for the Environment Novel, UV-Curable Nanotechnology-Enabled Coatings Highly Weather-Resistant Radiation-Curable Monomers and Oligomers for Exterior Applications Konica Minolta — Sensing Success for Viracon Self-Crosslinkable Thermosetting Acrylics for Use in Water-Dilutable Coatings Paint and Criminal Forensic Science Supplier and Application/Curing Showcases Materials Watch Classifieds Advertiser Index

Paint & Coatings Industry - November 2008

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